Using the 'Acapella' app, the pair went against each other in a series of sing-offs! They belted out some hits; a few Christmas songs and - don't worry - they covered their guilty pleasures... With glowing, flashing glasses, of course.

And once you've finished deciding who won each round, make sure you stick around for the video, to see Conor Maynard discussing, well, going to the toilet...